Fluid handling device

ABSTRACT

A device for handling a fluid to be introduced into a fluidic device is described. The fluid handling device is designed for alignment with a fluidic device, such as a microfluidic device, where an exit port on the device aligns with one or more apertures in the fluidic for exchange of fluids there between. The fluid handling device includes one or more channels, with at least two pistons spaced apart contained in one or more of the channels. The gap between neighboring pistons define a space between the pistons for containing a fluid. Movement of the pistons from a first position to a second position is effective to move fluid from the fluid handling device into the fluidic device.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present utility application claims priority to O'Connell's U.S.Provisional Application No. 60/852,334, filed Oct. 16, 2006, andentitled FLUID HANDLING DEVICE, the contents of which are incorporatedherein by reference.

TECHNICAL FIELD

The subject matter described herein relates to a fluid handling devicethat interfaces with a microfluidic device. The fluid handling device iscapable of, for example, introducing a fluid to the microfluidic device,storing a fluid prior to or after introduction to a microfluidic device,and directing fluid movement into and from a microfluidic device.

BACKGROUND

Microfluidic devices and systems provide improved methods of performingchemical, biochemical and biological analysis and synthesis.Microfluidic devices and systems allow for the performance ofmulti-step, multi-species chemical operations in chip-based microchemical analysis systems. Chip-based microfluidic systems generallycomprise conventional ‘microfluidic’ elements, and are capable ofhandling and analyzing chemical and biological specimens.

Many methods have been described for interfacing fluids, e.g., samples,analytes, reagents, with microfluidic systems. In conventionalmicrofluidic systems, the structures and methods used to introducesamples and other fluids into microfluidic substrates often limit thecapabilities of the microfluidic systems. For example, conventionalmicrofluidic systems may include a separate sample introduction channelfor introducing a sample to a microchannel for processing. The sample isfirst introduced into the sample channel and transported through thesample channel to the microchannel. Another method for introducing afluid involves the use of sample wells or reservoirs in communicationwith the microchannel for holding a relatively larger supply of thesample. Reservoirs are structures which accommodate a significantlygreater volume of fluid than the microfluidic channel. A relativelysmall portion of the sample supply in the sample well or reservoir isintroduced into the microchannel.

When working with fluids in conventional macroscopic volumes, fluidmetering is relatively straightforward. In microfluidic volumes,however, fluid metering is considerably more difficult. Most, if notall, microfluidic systems require some interface to the conventionalmacrofluidic world. Using conventional macrofluidic techniques, thesmallest volume of liquid that can be generated is a droplet, typicallyranging in volume between about 1-100 microliters. At the low end ofthis volumetric range it is difficult to consistently create dropletshaving a reasonably low volumetric standard deviation. For applicationsin which fluidic metering accuracy is desired, such as in chemicalsynthesis or quantitative analysis, there remains a need for introducingan accurate quantity of reagents or samples to a microfluidic device.

Accordingly, there exists a need for devices and methods capable ofinterfacing with a microfluidic device for introduction of microfluidicvolumes of fluid.

The foregoing examples of the related art and limitations relatedtherewith are intended to be illustrative and not exclusive. Otherlimitations of the related art will become apparent to those of skill inthe art upon a reading of the specification and a study of the drawings.

BRIEF SUMMARY

The following aspects and embodiments thereof described and illustratedbelow are meant to be exemplary and illustrative, not limiting in scope.

In one aspect, a device for introducing a fluid into a fluidic device isprovided. The device comprises a substrate having a first inlet port, afirst outlet port, a first channel extending between the first outletport and the first inlet port, and a first exit port disposed along thechannel between the first inlet port and the first outlet port. Thefirst channel contains at least two pistons spaced apart from oneanother to define a space between the pistons for containing a fluid,wherein the substrate is adapted to mate with the fluidic device suchthat the first exit port is aligned with an aperture in the fluidicdevice. Movement of the pistons from a first position to a secondposition in the first channel is effective to introduce fluid in thefirst channel through the first exit port and into the fluidic device.

In one embodiment, one of the at least two pistons is positioned overthe first exit port when the pistons are in the first position.

In another embodiment, one of the at least two pistons is positionedover the first exit port when the pistons are in a third position in thefirst channel.

In yet another embodiment, the device further comprises an actuatoradapted for connection with the first inlet port of the first channel,at least part of the actuator being dimensioned for insertion into thefirst-channel to effect movement of at least one of the at least twopistons in the first channel.

An exemplary actuator, in one embodiment, is a plunger. In otherembodiment, the actuator is a ratchet or an elongate bar with at leastone opening through which the first channel extends.

The device further includes, in another embodiment, a first wastechannel in fluid communication with an aperture in the microfluidicdevice.

In one embodiment, at least one piston is positioned in the wastechannel.

The device, in still another embodiment, further comprises a secondchannel extending between a second inlet port and a second outlet port,and a second exit port disposed along the second channel between thesecond inlet and second outlet ports. The second channel contains atleast two pistons spaced apart from one another to define a spacebetween the pistons for containing a fluid.

In one embodiment, the second channel also contains an actuator adaptedfor connection with the second inlet port of the second channel, atleast part of the actuator being dimensioned for insertion into thesecond channel to effect movement of at least one of the at least twopistons in the second channel.

The device, in still another embodiment, further includes a second wastechannel in fluid communication with a second aperture in the fluidicdevice.

In yet another embodiment, the fluid handling device comprises threepistons defining a first space and a second space between adjacentpistons, wherein a first fluid is contained in the first space and asecond fluid is contained in the second space. In one embodiment, thefirst fluid and the second fluid are different.

In one embodiment, movement of the pistons between the inlet port andthe outlet port provides sequential introduction of the first fluid andthe second fluid into the fluidic device.

In another aspect, a device for introducing a fluid into a fluidicdevice is provided. The device is comprised of a substrate comprising aninlet port, an outlet port, a first channel extending between the inletport and the outlet port, and a first exit port positioned along thefirst channel between the inlet port and the outlet port. The substrateis adapted for mating with the fluidic device. At least two pistons aredisposed within the first channel, the at least two pistons being spacedapart to define a space for containing a fluid. The device also includesa second channel in the substrate, the second channel terminating in afirst port at a first end of the channel and having a second portdisposed along the second channel. An actuator at least partlypositioned within the first channel is for movement of at least one ofthe at least two pistons.

In one embodiment, the actuator is in contact with at least one of theat least two pistons.

In still another aspect, a system for analysis of an analyte in a sampleis provided. The system comprises a fluidic device having a first port;and fluid handling device as set forth above. In a preferred embodiment,the fluid handling device is planar.

In addition to the exemplary aspects and embodiments described above,further aspects and embodiments will become apparent by reference to thedrawings, which are schematic and which are not intended to be drawn toscale. In the figures, each identical or nearly identical component thatis illustrated in various figures typically is represented by a singlenumeral. For purposes of clarity, not every component is labeled inevery figure, nor is every component of each embodiment shown whereillustration is not necessary for an understanding by one of ordinaryskill in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C are schematic illustrations of one embodiment of the devicedescribed herein, where the device is shown alone (FIGS. 1A-1B) andmated with a microfluidic device (FIG. 1C);

FIGS. 1D and 1E are schematic illustrations of the spiral well used insome embodiments of the device;

FIGS. 2A-2C are schematic illustrations of a single channel of oneembodiment of the device described herein, showing the positions of twopistons in the channel before release of a fluid therefrom (FIG. 2A),during release of a fluid (FIG. 2B), and after release of a fluid (FIG.2C);

FIGS. 3A-3B are schematic illustrations of a single channel of oneembodiment of the device described herein, showing the positions of asingle piston in the channel with respect to a channel aperture;

FIGS. 4A-4D are schematic illustrations of a ratchet component foractuating movement of pistons in a channel of one embodiment of thedevice;

FIGS. 5A-5D are schematic illustrations of an embodiment for actuatingmovement of pistons in a channel of one embodiment of the device, wherea sliding bar is positioned in the fluid handling device;

FIGS. 6A-6D are schematic illustrations of another embodiment foractuating movement of pistons in a channel of one embodiment of thedevice, where a movable rod is positioned in the fluid handling device;

FIGS. 7A-7D are schematic illustrations of another embodiment forinitiating movement of pistons in a channel the fluid handling device;

FIG. 8 shows a method of using the fluid handling device, where a fluidin a channel is moved to an adjacent channel for mixing, prior tointroduction of the fluid into a microfluidic device;

FIGS. 9A-9B show another embodiment of the fluid handling device formixing fluids; and

FIGS. 10A-10C show an embodiment of a device for dispensing one or morefluids.

DETAILED DESCRIPTION I. Definitions

The term “microfluidic” as used herein refers to structures or devicesthrough which one or more fluids are capable of being passed or directedand at least one fluid channel having a cross-sectional dimension ofless than about 1000 microns (1 millimeter).

“Channel”, as used herein, means a feature on or in a microfluidicdevice substrate that can at least partially confine and direct the flowof a fluid. Preferably a channel has an aspect ratio (length to averagecross sectional dimension) of at least 2:1, more typically at least 3:1,5:1, or 10:1. The feature can be a groove or other indentation of anycross-sectional shape (curved, square or rectangular) and can be coveredor uncovered. A channel generally will include characteristics thatfacilitate control over fluid transport, e.g., structuralcharacteristics (an elongated indentation) and/or physical or chemicalcharacteristics (hydrophobicity vs. hydrophilicity) or othercharacteristics that can exert a force (e.g., a containing force) on afluid. The channel may be of any size, for example, having a largestdimension perpendicular to fluid flow of less than about 5 or 2millimeters, or less than about 1 millimeter, or less than about 500microns, less than about 200 microns, less than about 100 microns, orless than about 50 or 25 microns. Larger channels, tubes, etc. can beused in the device for a variety of purposes, e.g., to store fluids inbulk or to direct fluid flow to a certain region of the device or of amicrofluidic device. The dimensions of the channel may also be chosen,for example, to allow a certain volumetric or linear flow rate of fluidin the channel. Of course, the number of channels and the shape of thechannels can be varied by any method known to those of ordinary skill inthe art.

“Integral”, as used herein, means that the portions are joined in such away that they cannot be separated from each other without cutting orbreaking the components from each other.

The term “plug” refers to matter in the shape of a cylinder and havingthe diameter of the inside of the channel. A plug can be a solid objectin the channel, or a volume of fluid that occupies a space in thechannel, the space being defined by pistons in the channel.

In the claims, as well as in the specification, all transitional phrasessuch as “comprising”, “including”, “having”, “containing”, “involving”,“composed of”, “made of”, “formed of” and the like are to be understoodto be open-ended, i.e. to mean including but not limited to. Thetransitional phrases “consisting of” and “consisting essentially of” areunderstood to be closed or semi-closed transitional phrases,respectively, as set forth in the United States Patent Office Manual ofPatent Examining Procedures, section 2111.03.

II. Device

In a first aspect, a device that interfaces with, or is an integral partof, a microfluidic device for introduction of a fluid from the device tothe microfluidic device is provided. In another aspect, a device capableof delivering one or more discrete plugs of fluid is described, thedevice optionally capable of mating with a microfluidic device. Thesevarious aspects will now be discussed.

FIGS. 1A-1B are plan views of a device designed to interface with amicrofluidic device and introduce a fluid into the microfluidic device.With initial reference to FIG. 1A, device 10 is formed on a (preferablyplanar) substrate 12. A channel 14 is formed in or on the substrate, thechannel extending between an inlet port 16 and an outlet port 18. Inthis embodiment, the inlet and outlet ports are disposed at first andsecond ends, 20, 22, respectively, of the substrate, however, it will beappreciated that the inlet and/or outlet ports need not be terminallypositioned.

The channel 14 contains one or more pistons, such as pistons 24, 26, 28,30. The pistons are preferably fluid impervious plugs disposed in thechannel and sized for sealing engagement with the channel. In oneembodiment, the pistons are formed of an elastomeric material, such as afluoroelastomer (Viton®), butadienes such as polychloroprene(Neoprene®), silicone rubber, and the like. Preferably, the materialfrom which the piston is formed is solvent resistant. In anotherembodiment, the pistons are a plug of, for example, an oil or a wax.

The device embodiment illustrated in FIG. 1A has four pistons in channel14, where the pistons are in a spaced apart to define a volume betweenadjacent pistons. For example, a space 32 is defined by neighboringpistons 24, 26; space 34 is defined by neighboring pistons 26, 28; andspace 36 is established by pistons 28, 30. Piston 24 has a first end 38and a second end 40. Piston 26 has a first end 42 and a second end 44.Space 32 is defined by the gap between second end 40 of piston 24 andfirst end 42 of piston 26. It will be appreciated that as few as twopistons can be positioned in the channel, or considerably more pistonscan be used, depending on the channel length and application. In oneembodiment, a device comprising two pistons per channel is contemplated.In other embodiments, a device comprising three, preferably four, andstill more preferably five, pistons per channel is contemplated.

Spaces or gaps 32, 34, 36, in various embodiments, contain a fluid,which intends a liquid or a gas. In a preferred embodiment, the fluid isa liquid. Spaces 32, 34, 36 can comprise the same or different fluids,depending on the application. In one embodiment, the fluid contained inthe space between two neighboring pistons has a volume of in the rangeof between about 1-50 μL, more preferably of between about 1-30 μL, andstill more preferably of between about 1-20 μL. In a preferredembodiment, a sample volume in the range of between about 1-5 μL iscontained in a spaced between neighboring pistons, for introduction intoa microfluidic device or for dispensing from the fluid handling devicean amount of preferably at least about 70%, more preferably at leastabout 80%, still more preferably at least about 90% of the samplevolume.

An exit port 48, shown in phantom in FIG. 1A, and visible in FIG. 1B,which shows the opposing side of device 10, provides communication withthe interior of channel 14 and the external surroundings. Exit port 48is disposed at any position along channel 14 between the inlet andoutlet ports. In use, the pistons in the channel are moved from a firstposition to a second position, and in some embodiments to subsequentpositions. For example, piston 24 is moved, typically in concert withthe other pistons in the channel, past exit port 48. When second end 40of piston 24 passes over exit port 48, fluid contained in space 32 flowsthrough exit port 48. As seen in FIG. 1C, a microfluidic device 50 isaligned with device 10 to accept fluid contained in space 32 through anaperture in the microfluidic device (not visible). Alignment members 52,54 can be provided to ensure that exit port 48 is correctly aligned withan aperture in the microfluidic device, for introduction of fluid fromdevice 10 into, for example, a sample well or channel of microfluidicdevice 50. For example, device 50 includes a microfluidic channel 56.

It will be appreciated that the fluid handling device can be a unitseparate and discrete from the microfluidic device, as illustrated inFIGS. 1A-1C, or can be integral with a microfluidic device. An devicewherein the microfluidic channels, wells, reaction chambers, etc. are onthe same substrate or on an integrally formed substrate with thechannel(s) of the sample handling device is contemplated.

Conventional fluidic devices use circular or elongate read wells tocontain fluid, e.g., for reading with an optical device. Unfortunately,due to the aspect change from small channels to large circular orelongate areas, air bubbles in the fluidic system tend to becomeentrapped, reduces the volume of the sample in the well and causingerrors in the measurement of volume. In some embodiments, themicrofluidic device 50 incorporates spiral read wells 57 to avoid theformation of air bubble in the wells. The spiral wells are first shownin FIG. 1C. FIGS. 1D and 1E shown an enlarged view of a spiral well 57(FIG. 1E) compared to a conventional well 58, which tend to accumulateair bubbles 59 (FIG. 1D).

As mentioned above, pistons disposed in a channel are capable ofmovement from an initial position to one or more subsequent positions.In one embodiment, as a result of piston movement, one or more of thepistons serve as a valve, as illustrated in FIGS. 2A-2C. FIG. 2A shows achannel 60 containing pistons 62, 64. Pistons 62, 64 are in a spacedapart relationship to define a space 66 between neighboring piston ends,i.e., end 62a of piston 62 and end 64a of piston 64. An exit port 68 isdisposed along the length of channel 60 to provide fluid communicationbetween the channel interior and the environment exterior to thechannel. Piston 62, in its first position, obstructs exit port 68, asseen in FIG. 2A. In this position, piston 62 acts as a valve in its“off” position. Applying force in the direction indicated by the arrow70 causes the movement of pistons 62, 64, to a second position wherepiston 62 no longer obstructs exit port 68 (FIG. 2B). That is, piston 62in its capacity as a valve has moved to its “on” position. In thisposition, fluid contained in space 66 can travel through exit port 66,in the direction indicated by arrow 72. Continued movement of thepistons in the direction of arrow 70 achieves movement of the pistons toa subsequent position, in this case to a third position, as illustratedin FIG. 2C. Piston 64 is positioned to obstruct exit port 68, i.e., thepiston acts as a valve in an “off” position, so that fluid from theenvironment external to the channel does not enter the channel. Releaseof fluid contained in space 66 results in a reduction in the spacedefined by pistons ends 62 a, 64 a, as illustrated in FIG. 2C.

The pistons illustrated in FIGS. 2A-2C include a central portion havinga smaller outer diameter than the piston ends. It will be appreciatedthat the shape of the pistons can vary and is not critical to the devicedescribed herein. A skilled artisan can envision alternative shapes thatachieve the function of the pistons required for operation of thedevice.

In some embodiments, movement of the pistons in a channel requiresgreater force than expelling fluid out an exit port, and, e.g., into achannel of a microfluidic device. Thus, the force applied by anactuating member to move a first piston from a first position to asecond position exceeds the force needed to expel fluid from between afirst piston and a second piston. In this manner, in some embodiments, afirst piston functions as a valve, moving from a first piston (i.e., an“off” position, where the piston obstructs fluid flow through an exitport), to an “on” position (i.e., where fluid flow through a port ispermitted). Once the first piston is moved from its “off” position toits “on” position, subsequent force applied by an actuating member,causes fluid to flow out the exit port as a second, neighboring pistonmoves toward the first position, which remains substantially stationaryin the channel. Only when fluid has flowed from the exit port and thesecond piston has contacted the first piston will the first piston againmove in response to force applied to the actuating member.

With continuing reference to FIG. 1A, device 10, in some embodiments,can include a waste channel 80. Waste channel 80 as depicted in FIG. 1Ais parallel to channel 14, however different orientations of the twochannels is possible and is contemplated. Waste channel 80 has an inletport 82 and an outlet port 84. Inlet port 82 is visible in the deviceorientation shown in FIG. 1B. When the device is mated and aligned witha microfluidic device, as shown in FIG. 1C, inlet port 82 is aligned toreceive fluid from the microfluidic device.

In one embodiment, the waste channel is coated with or contains anabsorbent material, to absorb or immobilize fluid waste in the wastechannel. Absorbent materials are well known in the art and includemoisture-wicking fabrics, dried hydrogels prepared from, for example,polyvinyl alchol, sodium polyacrylate, acrylate copolymers withhydrophilic moieties, cross-linked poly(ethylene oxides),polyvinylpyrrolidone, and others.

In another embodiment, the waste channel optionally includes one or morepistons. An exemplary embodiment is set forth in FIGS. 3A-3B. Channel 90includes a piston 92 situated on one side of an inlet port 94. All or aportion of channel 90 can contain an absorbent material, such asmaterial 96. In use and when inlet port 94 is in fluid-receivingalignment with an aperture in a microfluidic device, fluid is receivedinto channel 90 via inlet port 94. The fluid is biased to flow into theregion containing the absorbent material by the wicking action providedby the absorbent material. At a desired time, piston 92 can be movedfrom its initial position to a second position, as shown in FIG. 3B. Inits second position, fluid entering the channel via inlet port 94 isblocked from flowing into the region containing the absorbent material,and is directed to a different channel region indicated in the figure asregion 96. It will be appreciated that channel region 96 can optionallyinclude a same or different absorbent material. A skilled artisan willrecognized that this embodiment provides a means to separate fluidscollected in the waste channel, to prevent undesired interactions, topermit identification of fluid collected in the waste channel, or otherreasons.

In another embodiment, the device includes more than one channel and/ormore than one waste channel. Returning to the device illustrated in FIG.1A, the device is depicted with two channels, channel 14 and a channel100, which extends between an inlet port 102 and an outlet port 104.Channel 100 contains one or more pistons, such as pistons 106, 108, 110,112. The one or more pistons are in a spaced apart to define a space orgap between neighboring pistons, for retention of a fluid in the space.An exit port 114, visible in FIG. 1B, along channel 114 provides fluidicaccess between the channel interior and the exterior environment.

The device embodiment shown in FIGS. 1A-1C also includes a second wastechannel 116, having features similar to that described for the firstwaste channel 80. In particular, waste channel 116 has an inlet port118, for receiving a fluid from the environment exterior to the device,such as receipt of a fluid from a microfluidic device mated with thedevice, as shown in FIG. 1C. As with waste channel 80, channel 116 isshown in a parallel orientation with channel 100, however otherorientations are possible.

As noted above, the pistons in each channel are slidably movable from afirst position to one or more subsequent positions by an actuatingelement. An actuating element, or means for actuating, for moving thepistons along the channel can be a device as simple as a plungerinserted into the channel to the various embodiments of actuatingelements set forth in FIGS. 4-7, now to be described.

In one embodiment, as shown in FIGS. 4A-4D, the actuating means is inthe form of a ratcheting member. FIG. 4A shows a plurality of pistons120, 122, 124, 126, 128, in a spaced-apart relationship to define aspace between neighboring pistons for containing a fluid, indicated inthe drawing as fluids 130, 132, 134, 136. A channel in which the seriesof pistons separated by regions of fluid resides is not shown in FIG. 4Ato simplify viewing, however FIGS. 4C-4D illustrate a positionalarrangement with a channel of a fluid handling device. Adjacent, andpreferably in direct contact with, a terminal piston, such as piston120, is a ratchet member 138. Ratchet member, best seen in FIG. 4B,includes a terminal portion 140 for abutment with, preferably, aterminal piston. A catch, or pawl, 142 is attached to the terminalportion of the ratchet member, by a flexible arm 144. A fluid handlingdevice 146 has a series of teeth, such as teeth 148, 150, which definedetentes (or notches), for engaging the ratchet member pawl 142, as seenbest in FIG. 4D. Pawl 142 in FIG. 4C is positioned in the detente formedbetween teeth 148, 150. To advance the ratchet member, pawl 142 ispressed by the user to disengage the pawl from its detente between teeth148, 150. A spring 152 may be employed to urge the ratchet member 138 inthe direction of arrow 154. It will be appreciated that the spring canbe positioned elsewhere in the device. It will also be appreciated thatone or more edges or corners of pawl 142 and teeth, such as 148, 150,can be chamfered, such as chamfered edge 155 of tooth 156 to easemovement of the pawl between teeth.

Another embodiment of an actuating element is shown in FIGS. 5A-5D. Aslide member 160 has a plurality of openings, such as opening 162. Thenumber of openings typically corresponds to the number of channels in aparticular fluid handling device (FIG. 5A). A solid region is positionedbetween neighboring openings, such as solid region 164 adjacent toopening 162. Slide member 160 is positioned in a fluid handling device,such as device 166, shown in partial view, wherein several channels inthe device are illustrated (FIGS. 5B-5D).

FIGS. 5B-5D depict the device 166 in three stages of operation, wherethe position of slide member 160 and adjacent slide member 168 controlthe progression of s a piston 300 into the channel 301, by force ofcompressed springs 170. Each spring is at first held under tension,e.g., between solid region 164 and an equivalent solid region onadjacent slide member 168 (FIG. 5B).

When slide member 160 is moved to allow a spring 170 to pass through theopening 162, the piston 300 is forced into the channel 301 by an amountdetermined by the spring 170 (FIG. 5C). FIG. 5D shows the next stage ofoperation, when adjacent slide member 168 is moved in a similar manner,forcing the piston 300 into the channel 301 by another defined amount orincrement.

It will be appreciated that one or more slide members and springs can bearranged to permit successive advancement of pistons aligned in achannel.

FIGS. 6A-6D illustrate yet another embodiment of an actuating element,to achieve movement of a piston 300 into a channel 301 of the fluidhandling device 166. In this embodiment, rotating bar 180 has a seriesof openings, such as opening 182, separated by solid regions, such asregion 184 (FIG. 6A). The bar is adapted to fit in a fluid handlingdevice 186, shown in partial view in FIGS. 6B-6D.

FIGS. 6B-6D depict the device 186 in three stages of operation, wherethe position of rotating bar 180 and adjacent rotating bar 185 (shown inside view) control the progression of piston 300 into the channel 301,by force of compressed springs 170. Each spring is at first held undertension, e.g., between solid region 184 and an equivalent solid regionon adjacent rotating bar 185 (FIG. 5B).

When rotating bar 180 is rotated to allow a spring 170 to pass throughthe opening 182, the piston 300 is forced into the channel 301 by anamount determined by the spring 170 (FIG. 6C). FIG. 6D shows the nextstage of operation, when adjacent rotating bar 185 is moved in a similarmanner, forcing the piston 300 into the channel 301 by another definedamount or increment.

It will be appreciated that one or more rotating bars and springs can bearranged to permit successive advancement of pistons aligned in achannel.

FIGS. 7A-7D show another embodiment of an actuating element, where theactuating element is formed of a material that responds to heat,typically by entering a physically weakened condition as in becomingmore fluid or melting. In this embodiment, a fuse member 200 in the formof an elongate strip of a heat-responsive material is used (FIG. 7A).The fuse member 200 is adapted to fit in a fluid handling device 202,shown in partial view in FIGS. 7B-7D.

FIGS. 7B-7D depict the device 202 in three stages of operation, where afirst fuse member 200 and adjacent fuse member 204 control theprogression of piston 300 into the channel 301, by force of compressedsprings 170. Each spring is at first held under tension, e.g., betweenthe fuse members 200, 204 (FIG. 7B).

When the first fuse member 200 is melted, e.g., by application of heat,spring 170 passes through the melted remains of fuse member 200, and thepiston 300 is forced into the channel 301 by an amount determined by thespring 170 (FIG. 7C). FIG. 7D shows the next stage of operation, whenadjacent fuse member 204 is melted in a similar manner, forcing thepiston 300 into the channel 301 by another defined amount or increment.

It will be appreciated that one or more fuse members and springs can bearranged to permit successive advancement of pistons aligned in achannel.

FIG. 8 shows a fluid handling device 220 having a series of parallelchannels, such as channels 222, 224. Channel 222 is connected to channel224 by channel 223. Channel 222 comprises a plurality of pistons, 226,228, 230, 232, 234. Channel 224 comprises two pistons, 236, 238. Piston238 is initially positioned to block channel 223 (as in a valve in the“off” position), but is movable in the direction of arrow 240 such thatfluid contained in the space between pistons 236, 238 flows into channel223. The fluid flows into channel 222 and enters the space betweenneighboring pistons 234, 232 residing in channel 222. The fluid mixeswith a solid or liquid reagent in the space between pistons 234, 232.Activation of the actuating element 242 advances the pistons in channel222, dispensing sequentially the fluid between neighboring pistons 234and 232; 232 and 230; 230 and 228; and 228 and 226.

FIGS. 9A-9B show a piston 242 with a central bore or “through-hole” 244(visible only in FIG. 9B). Piston 242 is one of a plurality of pistonsarranged for insertion, or already inserted into, a channel of a fluidhandling device. In this embodiment, piston 242 is disposed between aterminal piston 246 and a neighboring piston 248. A space 250 is definedbetween the terminal piston 246 and piston 242 for containing a firstfluid. A second space 252 is defined between piston 242 and neighboringpiston 248 for containing a second fluid. Activation of actuatingelement 254 to advance the pistons results in movement of the firstfluid in space 250 into through-hole 244 for contact, and mixing, withthe second fluid in space 252. At the same time, the remaining pistonsare advanced, and fluid is introduced into a mated microfluidic device.Subsequent movement of the actuating element further advances one ormore of the pistons, for introduction of fluid contained between theneighboring pistons into the microfluidic device. It will be appreciatedthat a piston with a through-hole or central bore may include a valve orplug to prevent fluid from moving through the bore until such movementis desired. The central bore of the piston can be adapted with, forexample, a one-way check valve or with a plug of oil or wax at one endof the bore. It will also be appreciated that the system can also bearranged such that all the pistons have a central hole with a valve anda liquid held in between at least two pistons. The liquid is induced tomove in to the exit channel by opening the first piston's valve andpushing the series of pistons and liquid forward. The next piston canopen its valve upon contact with the first by a mechanical or othermeans to release the liquid behind it to enter into the central bore ofthe pistons and into the exit channel. This arrangement can be repeatedas many times as desired.

An alternative embodiment of a fluid handling device is illustrated inFIGS. 10A-10C. Device 260 is comprised of a conventional syringe,comprised of a cylindrical barrel 262 and a plunger 264. The barrel hasan end with a large opening for receiving plunger 264 and an end with asmall opening for communicating with a needle 272. Plunger 264 ismoveable in a sliding, fluid-sealing arrangement within barrel 262. Oneend of plunger 264 is comprised of two or more pistons, such as pistons266, 268. A space 270 exits between adjacent ends of neighboring pistons266, 268. A needle 272 extends from a skin piercing distal tip 274 to aproximal end 276 fixed in any one of various known manners to device260. Needle 272 extends through the pistons, as seen best in FIG. 10B.Needle 272 includes an fluid port 278, visible in FIG. 10C. In preferredembodiments, the needle 272 is positioned such that the fluid port 278is near the end of the cylindrical barrel 262 that has the smallopening. Movement of plunger 264 advances the pistons over needle 272.As the fluid contained in the spaces between neighboring pistons movesover fluid port 278, the fluid enters the port and is dispensed throughan opening in tip 274. It will be appreciated that tip 274 can beinserted through the skin or other tissue of a subject, or can beinserted into an aperture of a device.

The fluid handling device described herein can be fabricated from avariety of materials, and selection of a suitable material is within theknowledge of a skilled artisan. Exemplary materials include metals andplastics, including but not limited to rigid elastomers, synthetic andnatural rubber, glass, quartz, silicone rubber, and the like.

While a number of exemplary aspects and embodiments have been discussedabove, those of skill in the art will recognize certain modifications,permutations, additions and sub-combinations thereof. It is thereforeintended that the following appended claims and claims hereafterintroduced are interpreted to include all such modifications,permutations, additions and sub-combinations as are within their truespirit and scope.

1. A device for introducing a fluid into a fluidic device, comprising asubstrate having a first inlet port, a first outlet port, a firstchannel extending between the first outlet port and the first inletport, and a first exit port in the channel between the first inlet portand the first outlet port, said first channel containing at least twopistons spaced apart to define a space between the pistons forcontaining a fluid, wherein said substrate is adapted to mate with thefluidic device such that the first exit port is aligned with an aperturein the fluidic device, and wherein movement of the pistons from a firstposition to a second position in the first channel is effective tointroduce fluid in the first channel through the first exit port andinto the fluidic device.
 2. The device of claim 1, wherein one of the atleast two pistons is positioned over the first exit port when thepistons are in the first position.
 3. The device of claim 1, wherein oneof the at least two pistons is positioned over the first exit port whenthe pistons are in a third position in the first channel.
 4. The deviceof claim 1, further comprising an actuator adapted for connection withthe first inlet port of the first channel, at least part of saidactuator being dimensioned for insertion into the first channel toeffect movement of at least one of the at least two pistons in the firstchannel.
 5. The device of claim 4, wherein the actuator is a plunger. 6.The device of claim 4, wherein the actuator is a ratcheting member. 7.The device of claim 4, wherein the actuator is an elongate bar with atleast one opening through which the first channel extends.
 8. The deviceof claim 1, further comprising a first waste channel in fluidcommunication with an aperture in the microfluidic device.
 9. The deviceof claim 8, further comprising at least one piston positioned in thewaste channel.
 10. The device of claim 1, further comprising a secondchannel extending between a second inlet port and a second outlet port,and a second exit port disposed along the second channel between thesecond inlet and second outlet ports, said second channel containing atleast two pistons spaced apart to define a space between the pistons forcontaining a fluid.
 11. The device of claim 10, further comprising anactuator adapted for connection with the second inlet port of the secondchannel, at least part of said actuator being dimensioned for insertioninto the second channel to effect movement of at least one of the atleast two pistons in the second channel.
 12. The device of claim 11,wherein the actuator is an elongate bar with at least two openingsthrough which first channel and the second channel extend.
 13. Thedevice of claim 10, further comprising a second waste channel in fluidcommunication with a second aperture in the fluidic device.
 14. Thedevice of claim 2, wherein said at least two pistons comprises threepistons defining a first space and a second space between adjacentpistons, wherein a first fluid is contained in the first space and asecond fluid is contained in the second space.
 15. The device of claim14, wherein the first fluid and the second fluid are different.
 16. Thedevice of claim 14, wherein movement of the pistons between the inletport and the outlet port provides sequential introduction of the firstfluid and the second fluid into the fluidic device.
 17. A device forintroducing a fluid into a fluidic device, comprising a substratecomprising an inlet port, an outlet port, a first channel extendingbetween the inlet port and the outlet port, and a first exit portpositioned along the first channel between the inlet port and the outletport, the substrate being adapted for mating with the fluidic device; atleast two pistons within said first channel, the at least two pistonsbeing spaced apart to define a space for containing a fluid, a secondchannel in the substrate, the second channel terminating in a first portat a first end of the channel and having a second port in the secondchannel, and an actuator at least partly positioned within the firstchannel for movement of at least one of the at least two pistons. 18.The device of claim 17, wherein the actuator is a plunger.
 19. Thedevice of claim 17, wherein the actuator is in contact with at least oneof the at least two pistons.
 20. The device of claim 17, wherein theactuator includes a ratchet mechanism for sequential advancement of theactuator in the first channel.
 21. The device of claim 17, wherein saidat least two pistons comprises three pistons defining a first space anda second space between adjacent pistons, wherein a first fluid iscontained in the first space and a second fluid is contained in thesecond space.
 22. The device of claim 21, wherein the first fluid andthe second fluid are different.
 23. The device of claim 21, whereinmovement of the pistons within the first channel provides sequentialintroduction of the first fluid and the second fluid into the fluidicdevice.
 24. A system for analysis of an analyte in a sample, comprisinga fluidic device having a first port; and a device according to claim 1or claim
 17. 25. The system of claim 24, wherein the fluidic device isplanar.
 26. The system of claim 24, wherein the fluidic device comprisesat least one spiral read well.